Research On Synthesis And Properties Of ZnO CeO₂ GaN And Bi₂O₃ Nanocrystallines

Nanomaterials have stimulated great interest because of its unique properties including surface effect, small size effect and quantum dimension effect, which differ from those of bulk substances and single molecular. The promising application value in areas such as electronics, optics, chemistry, ceramics, biology and medicine invokes great interest all over the world. Synthesis and characterize of zero-dimensional materials have been obtained great achivement since the 1980s. In recent years, there are great progress in one-dimensional (1D) and two-dimensional (2D) nanomaterials of synthesis and characterize. But the synthesis of 1D and 2D materials are still challenging. There are still some difficulities in controlling effictively the morphology and microstructure of nanomatirials.In this paper, ZnO, CeO₂, GaN and Bi₂O₃ nanomaterials have been synthesized successfully by hydrothermal method and chemical vapor deposition method. Their morphologies, microstructures have been charactirized, and some physical properties and growth mechanism have been researched systematically. The main results are as follows:ZnO nanorods have been fabricated by the chemical reaction of ZnCl₂ solution and NaOH solution. The ZnO nanorods are characterized with scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and powder X-ray diffraction (XRD). The results show these one-dimensional nanorods are single crystal with hexagonal structure. Additive reagent PEG is very important for the formation of ZnO nanorods. The PEG molecules adsorb Zn²⁺ and cause the increasement of the surface electronic charge density, the dicreasement of surface tension and nucleation energy. PEG has an important inductive function on growth tendency of ZnO nanostmctures. How the solution environment affects the morphology and dimension during the synthesis process of ZnO nanostructures has been discussed. The speed of ZnO₄^2- from liquid to crystal surface can be controlled in the environment of Alcohol-water, which is helpful to obtain uniform nanorods. If there is no alcohol in the solution, the speed of ZnO₄^2- from liquid to crystal surface can't be controlled, and only big asymmetry microrods can be obtained.